This species was previously considered to belong to L. hamiltoni, but was described as a new species, Leiopelma pakeka, in 1998 (Bell et al. 1998). There is ongoing discussion over the taxonomic status of these two species, which were subsequently declared evolutionarily significant units of the same species based on a study of partial 12 S ribosomal RNA and cytochrome b gene sequences (Holyoake et al. 2001) although no formal taxonomic changes were made. There is ongoing discussion and research into this subject.

Leiopelma pakeka has a small AOO of less than 6 km2 and is found in just 4 threat-defined locations, between which dispersal is not possible. As such, it is assessed as Vulnerable under the D2 criterion for restricted distribution, with the potential for threats (e.g. a rat or mustelid invasion to the Maud Island stronghold) to cause massive declines pushing the species into the Critically Endangered category over a short period of time. While the values for EOO and AOO and the small number of locations meet the thresholds for higher classification under criterion B, there is no evidence of extreme fluctuations or continuing decline in EOO, AOO, habitat, number of locations or number of mature individuals so the full criteria are not met, which is a result of effective conservation measures.

The Maud Island frog, L. pakeka, is found naturally only on Maud Island, Marlborough Sounds, South Island, New Zealand, where it was discovered in <0.2 km2 of remnant forest - all that remained after the majority of the island was cleared for farming (Crook et al. 1971).

Translocations in 1984-85 established a population at a new site on Maud Island, Boat Bay (with an area of approximately 0.1 km2), using 100 founder individuals. After this had shown signs of success, inter-island translocations were carried out to Motuara Island (1997 and 2014; site <0.1 km2) and Long Island (2005), both in Queen Charlotte Sound. Additional translocations were carried out in 2006 and 2012, with the aim of establishing a population on a mainland site, in a localized area of the Zealandia fenced sanctuary in Wellington (Newman et al. 2010). Monitoring indicates that the translocations to Motuara Island and Zealandia seem to have been successful, but there have been limited recaptures of translocated individuals on Long Island so it is unclear whether a population has established there.

Within its extent of occurrence of 452 km2, its map-based area of occupancy has been estimated at 6 km2. However, its true AOO is much closer to and probably less than 1 km2. Finally, while there are 5 sub-populations of this species, two are on the same island where the biggest threat is invasion by rats or mustelids. So the species is thought to occur in 4 threat-defined locations.

The population of L. pakeka on Maud Island has been the subject of demographic studies since 1976, with intensive monitoring carried out for the past 25 years in two defined ‘grids’. This monitoring has shown that the population size has remained relatively stable (Bell & Pledger, 2010). The total population on Maud Island has been estimated in different studies at 19,000 – 34,000 frogs (Bell & Bell, 1994; Bell & Pledger, 2010). Frogs are more abundant on the lower slopes of the forest, where the canopy is higher and there is a greater density of rocks on the forest floor (Bell and Bell 1994).

In total, 600 frogs have been translocated to Motuara Island, 101 frogs to Long Island, and 161 frogs have been released at the Zealandia sanctuary (30 of these individuals were sourced from captive frogs). While breeding has been recorded at Zealandia, and on Motuara Island the population has expanded well (E. Bell pers. comm. July 2015), the total population outside Maud Island is still likely to number fewer than 1,500 mature individuals. The fate of the Long Island population is unknown, but post-translocation monitoring has identified just a few recaptures.

Formerly, Leiopelma pakeka survived only in a small patch of remnant native coastal forest on a boulder bank on Maud Island, Marlborough Sounds. Translocations have introduced the species into similar habitat on both island sites and one mainland site.

Long-term monitoring has recaptured individuals over 40 years of age, thus its generation length is approximately 20 years. However, very little is known about the reproductive ecology of this nocturnal species, although it is known that small clusters (<15) of large unpigmented eggs are laid terrestrially in damp situations in sheltered areas on the ground or under rock piles. Eggs undergo direct development without a larval stage (Bell, 1985).

The introduction of non-native mammalian species (e.g. Rattus spp. and mustelid species) combined with deforestation was probably the major driver of the massive historical declines in both range and population size. Today introduced mammalian predators remain a potential threat; non-native species are currently kept from the islands through quarantine procedures and from the Zealandia sanctuary with a predator-proof fence (although mice can breach this fence). An invasion of mice onto Maud Island was discovered in 2013; an eradication programme began in 2014 and quarantine processes were improved, but the effects of this incursion remain to be seen.

Chytridiomycosis is a potential future threat; this disease has been identified in New Zealand in the closely relatedL. archeyi, but to date this disease has not been recorded at any of the sites whereL. pakeka occurs.

The populations beyond Maud Island remain very small, and the species is found in a small distribution in few locations, so is also vulnerable to stochastic events, including fire.

Through its Native Frog Recovery Group and 2013-2018 Native Frog Recovery Plan, the NZ Department of Conservation (DOC) administers conservation management of this species and permits appropriate species research.

Maud Island is now designated a Scientific Reserve which is managed by the New Zealand Department of Conservation for the benefit of native wildlife. While sheep are used for management in a small area, non-native herbivores have been excluded from the majority of the island, allowing natural forest regeneration to occur.

Several conservation translocations have been carried out to sites beyond Maud Island; in total, 600 frogs have been translocated to Motuara Island, 101 frogs to Long Island, and 161 frogs have been released at the Zealandia sanctuary (30 of these individuals were sourced from captive frogs). While breeding has been recorded at Zealandia and on Motuara Island, the total population outside Maud Island is still likely to number fewer than 1,000 mature individuals. The fate of the Long Island population is unknown; post-translocation monitoring has identified just a few recaptures so this translocation appears to have been less successful. Motuara Island and Long Island are managed by the New Zealand Department of Conservation.

Conservation Needed

Monitoring of translocated populations at Motuara Island and Long Island is required, in particular at Long Island where the fate of the translocated individuals is unknown. Monitoring on Maud Island should continue.

Maintaining existing biosecurity and hygiene protocols at island sites is essential for the continued survival of this species, and regular disease screening for chytrid should be carried out.

Lack of public awareness of cryptic native frogs does not aid conservation efforts; increased public awareness of this species would be of benefit.

Research Needed

There is still debate regarding the taxonomic status of this species with relation to Leiopelma hamiltoni – research is necessary to define whether these represent one or two species, as this has implications on conservation management.

Data, including life-history data necessary for developing population models and providing guidance for translocations, are lacking for this species, and research should continue to determine life-history parameters.

Development of captive husbandry techniques is necessary in order for the ex-situ population to play a valuable role in conservation management.